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Date:   Fri, 14 Dec 2018 10:32:55 +0100
From:   Daniel Vetter <daniel@ffwll.ch>
To:     Lyude Paul <lyude@redhat.com>
Cc:     dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        intel-gfx@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
        Daniel Vetter <daniel@ffwll.ch>,
        Dave Airlie <airlied@gmail.com>,
        Harry Wentland <harry.wentland@amd.com>,
        Jerry Zuo <Jerry.Zuo@amd.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        David Airlie <airlied@linux.ie>, linux-kernel@vger.kernel.org
Subject: Re: [WIP PATCH 06/15] drm/i915: Keep malloc references to MST ports
Message-ID: <20181214093255.GO21184@phenom.ffwll.local>
Mail-Followup-To: Lyude Paul <lyude@redhat.com>,
        dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        intel-gfx@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
        Dave Airlie <airlied@gmail.com>,
        Harry Wentland <harry.wentland@amd.com>,
        Jerry Zuo <Jerry.Zuo@amd.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        David Airlie <airlied@linux.ie>, linux-kernel@vger.kernel.org
References: <20181214012604.13746-1-lyude@redhat.com>
 <20181214012604.13746-7-lyude@redhat.com>
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On Thu, Dec 13, 2018 at 08:25:35PM -0500, Lyude Paul wrote:
> So that the ports stay around until we've destroyed the connectors, in
> order to ensure that we don't pass an invalid pointer to any MST helpers
> once we introduce the new MST VCPI helpers.
> 
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> ---
>  drivers/gpu/drm/i915/intel_connector.c | 4 ++++
>  drivers/gpu/drm/i915/intel_dp_mst.c    | 2 ++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_connector.c b/drivers/gpu/drm/i915/intel_connector.c
> index 18e370f607bc..37d2c644f4b8 100644
> --- a/drivers/gpu/drm/i915/intel_connector.c
> +++ b/drivers/gpu/drm/i915/intel_connector.c
> @@ -95,6 +95,10 @@ void intel_connector_destroy(struct drm_connector *connector)
>  	intel_panel_fini(&intel_connector->panel);
>  
>  	drm_connector_cleanup(connector);
> +
> +	if (intel_connector->port)

We set this as the first thing in intel_dp_add_mst_connector, so this
check isn't doing anything.

> +		drm_dp_mst_put_port_malloc(intel_connector->port);
> +
>  	kfree(connector);
>  }
>  
> diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> index f05427b74e34..4d6ced34d465 100644
> --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> @@ -484,6 +484,8 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
>  	if (ret)
>  		goto err;
>  
> +	drm_dp_mst_get_port_malloc(port);

Needs to be moved up where we assing intel_connector->port, or it'll
underflow on cleanup on error paths.

> +
>  	return connector;
>  
>  err:
> -- 
> 2.19.2
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch